Down hole self-adjusting tubing anchor



July'8, 1969 5. PAGE. JR

DOWN HOLE SELF-ADJUSTING TUBING ANCHOR Fi ed Feb. 14, 1967 SheetIA/vEA/rap. Jam 5. Pass ,Je.

United States Patent 3,454,091 DOWN HOLE SELF-ADJUSTING TUBING ANCHORJohn S. Page, In, Long Beach, Calif., assignor, by mesne assignments, toCook Testing Co., Long Beach, Calif., a corporation of California FiledFeb. 14, 1967, Ser. No. 616,121 Int. Cl. EZlb 23/04 U.S. Cl. 166-212 3Claims ABSTRACT OF THE DISCLOSURE An improved well tubing anchorfunctions in response to fluid pressure application to anchor tubing tothe well bore, remaining anchored during fluid pressure increaseaccompanied by tubing stretching, and also remaining anchored duringpressure fall-off. Tubing tension urges a wedge member upwardly to holdslip means anchored to the well bore, and release of the anchor can besecured by relieving tubing tension, as by lowering.

Background 0) the invention This invention relates generally to oil welltubing anchors and more particularly concerns a highly advantageousfluid pressure settable and tubing tension lockable tubing anchor.

When tubing in oil wells is not anchored to the casing, certain problemsresult. For example, on the down stroke of the well pump, the entirefluid load is transferred from the pump rods to the tubing causing it tobe stretched down the hole. Also on the down stroke, a dynamic impact iscreated, throwing a shock load onto the tubing. Instrument recordingsmeasuring the stresses on the top joint of the unanchored string inproducing wells show load reversals that are fitfy percent greater thanthe calculated fluid load pickup of the pump. Such recordings show thatthis additional force is applied onto the tubing with a sudden impact,the severity of which depends upon the pump diameter, the speed at whichthe pump descends, the amount of gas in the fluid and the amount offilling of the pump on the up stroke. Such dynamic impact of the downstroke shortens the life of the tubing thread sealing capability and theover all life of the pumping complex.

On the pump up-stroke, the rods pick up :part of the fluid load causingthe tubing to unstretch and engage the casing. This movement, typicallyoccurring many thousands of times a day, causes substantial tubing andeasing wear, as Well as rod wear. Further results of unanchoredbreathing tubing include lost pump efliciency and lost production,increased pulling and repair costs, excessive pumping unit and gear weardue to fluid load reversal shock transmitted to the entire pumpingsystem, and tubing buckling.

Efforts to alleviate the above problems have resulted in the provisionof various types of tubing anchors that operate to transfer fluid loadreversal shock forces to the casing, and which result in reduced tubing,casing and rod wear. However, in the case of mechanically operatedanchors, disadvantageous tubing manipulation is required to set theanchor, foreclosing its further adjustment down the hole to allow fortubing stretching without further tubing manipulation. Fluid pressureoperated anchors developed to avoid tubing manipulation setting havesuffered from the problem of anchor release upon fluid pressuredrop-01f. For example, where a cone is hydraulically actu- 3,454,091Patented July 8, 1969 ated into engagement with slips to urge them intoforcible engagement with a casing, the cone yields and releases theslips when the actuating fluid pressure drops otf. Such a device alsorequires several slips spaced about the tubing axis.

Summary of the invention The present invention has as its major objectthe provision of an improved fluid pressure responsive tubing anchorthat overcomes the above problems and that is further characterized by anumber of additional advantages including capacity for fluid pressuresetting and tubing tension locking of the anchor to the well bore.Basically, the anchor comprises a body adapted for carriage on a tubingstring into a well having a bore wall, slip means carried by and bodilymovable relative to the body at the side thereof toward and away fromthe bore wall, means including an actuator operable in response to fluidpressure application thereto to move the slip means generallylongitudinally of the body, and a wedging member carried by the body tourge the slip means toward and into gripping engagement with the borewall in response to actuator effected slip movement in a longitudinallydownward direction and to transmit string tension acting in alongitudinally upward direction to maintain the slip means wedged intogripping engagement with the bore wall during drop-off of fluid pressureapplication to the actuator.

Typically, therwedging member 'has an upwardly tapering wedge surfacelocated in the path of slip longitudinal movement effected by theactuator to urge the slip means generally away from the string axis inresponse to fluid pressure communication to the actuator. Since the slipmeans is displaced relative to the wedging member on the body, the sliptends to remain in engagement with the bore wall even though fluidpressure drop-ofl? relieves actuator force transmission to the slip.Further, the slip typically has wickers angled in such relation to theangularity of the wedge surface with respect to the string axis that theslip means adjusts downwardly while engaged with well bore as the tubingstretches downwardly during fluid pressure application to the actuator,the wedge surface blocking inward displacement of the slip means.

As a result, the apparatus functions hydraulically to anchor tubing tothe bore wall and remains anchored during fluid pressure increaseaccompanied by stretching of the tubing, as well as during fall-off asaccompanies pulling of the pump and fluid drainage down the hole; thetension of the tubing serves to urge the wedge member upwardly to holdthe slip means anchored to the casing bore, and release of the anchorcan be simply and rapidly accomplished by relieving tubing tension, asby lowering the tubing at the surface.

Other objects and advantages of the invention include the provision of aconnection between the body and the wedging member and characterized asshearable in response to predetermined longitudinal force transmissionby the connection imposed as a result of forcible elevation of the bodyin a well, whereby the slip means may be disengaged from the bore wallduring an emergency; the provision of a simple anchor constructioncomprising a body formed for attachment to standard string tubing as bywelding, the slip means, wedging member and actuator located at oneside'of the body and the slip means located in a body recess at thatside; and the provision of other highly advantageous constructionalfeatures as will appear.

These and other objects and advantages of the inven tion, as well as thedetails of illustrative embodiments, will be more fully understood fromthe following detailed description of the drawings, in which:

Brief description the drawing FIG. 1 is a vertical elevation showing theanchor installed in a tubing string in a well with a pump operated fromthe surface;

FIG. 2 is an enlarged vertical section showing the anchor as run into awell, before connection to the well bore;

FIG. 3 is a view like FIG. 2, but showing the anchor connected to thewell bore;

FIG. 4 is a view like FIG. 2, but showing the anchor during emergencyelevation in a well; and

FIGS. 5-7 are horizontal sections taken on lines 5-5, 66 and 7-7 of FIG.2.

Description of a preferred embodiment Referring first to FIG. 1, a wellcasing 10 is shown receiving a tubing string 11 comprising tubingsections 11a interconnected at 11b. Installed in the string is avertically reciprocable pump generally indicated at 12 and is operablein response to upward and downward movement of the pump rod string 13.The latter extends vertically within the tubing and is suspended fromthe walking beam 14 suitably driven at 15 for vertically reciprocatingthe pump rods. In operation, upon upward movement of the rod string,well fluid is drawn through the perforations 16 in the casing andupwardly into the tubing string via an inlet port 17, a valve ball 18then being lifted. Upon downward movement of the rod string, the ball 18seats to close the port 17, and a second ball 19 is lifted off its seatto admit fluid from the chamber 20 into the space 21 above the upperball 19 and into the tubing extending thereabovc. Such fluid so admittedstands in a column within the tubing and is lifted and lowered as therod string is reciprocated. Further, such fluid is removed from thestring at the surface via appropriate connections.

Also shown in FIG. 1 is the tubing anchor of the present invention,which is generally indicated at 22. Extending the description of FIGS. 2and 5-7, the anchor is shown to include a body 23, which mayadvantageously be yokeshaped as seen in FIGS. 5 and 6 and attached to astandard tubing section 11a as by welding thereto, indicated at 24. Forthis purpose, the body 23 may comprise a metal casting having a bore 25receiving the tubing section 11a. Attached to the upper terminal of thetubing section 11a is a tubular part 26 to form an upper extension ofthe tubing and having external threading at 27 to attach to a collar 11bconnecting to the next upper section of tubing 11a as is clear fromFIG. 1. The body 23 includes arms 28 which are ircularly spaced at 29and which have terminals 30 formed to grip engage the bore 31 of thecasing when the anchor is attached to the casing as seen in FIG. 3. Twopairs of such arms are provided at upper and lower elevations asindicated.

Another element of the anchor comprises slip means carried by and bodilymovable relative to the body 23 at the side thereof toward and away fromthe bore wall. In this regard, the slip means may typically comprise thesingle slip member 32 received within a side recess 33 formed in thebody 23, and extending generally longitudinally therein. Also receivedwithin the recess 33 is a wedging member 34 carried by the body to urgethe slip toward and into gripping engagement with the bore Wall inresponse to slip movement in a longitudinally downward direction. Inthis regard the wedging member has T-slot or tongue and grooveconnection with the slip at the location 35, and the slip and wedgingmember have slidable interengagement along their upwardly taperinginterengaged surfaces at 36.

Such movement of the slip member relative to the wedging member iseffected by means including an actuator operable in response to fluidpressure application thereto to move the slip generally longitudinallyof the body. One such actuator of unusually advantageous constructionincludes a piston 37 having a seal disc 38 providing a piston surface 39for receiving fluid pressure introduced within the cylinder 40 whichextends longitudinally vertically at the slip side of the tubing 11a.The cylinder is releasably connected at 41 with the part 26, the latterhaving porting 42 to communicate fluid pressure from the interior of thetubing to the actuator piston surface 39. In this regard, the body 23,tubing 11a carrying the body 23, and the part 26 may be considered asone integral body.

Such fluid pressure may be considered to arise under variouscircumstances, one of which is the existence of the production fluidreceived within the tubing string during operation of the pump aspreviously described. Thus, when the head of the liquid within thestring applied via the porting 42 to the piston surface 39 is suflicientto overcome the upward force exerted by a compression spring 43 actingon the piston, the latter is urged downwardly within the cylinder 40 todisplace the piston rod 44 downwardly. The rod has a lower projection44a connected to a second member 45, which may be considered as part ofthe actuator, and which also projects within the recess 33. Member 45has a wedge surface 46 tapering downwardly and inwardly to slightextent, and engaging the correspondingly tapered upper surface 47 of theslip 32 for urging the slip generally longitudinally and away from theaxis 48 in response to downward displacement of the member 45. Member 45also serves to retain the slip, i.e., suspend it by virtue of a suitableT-slot connection therewith, as indicated by the broken line 49. Thus,in the absence of sufficient fluid pressure downward exertion on theactuator, the actuator piston is urged upwardly by the spring 43, andthe retainer 45 holds the slip 32 in raised position, the slip moving toinwardmost position as seen in FIG. 2 due to the downward and inwardangularity of the T-slot connection between the retainer member 45 andthe slip.

As the level of the production liquid pumped into the tubing stringrises, the weight of that liquid transferred to the string duringdownward stroking of the rods 13 acts to downwardly stretch the stringwithin the well. Such stretching tends to progressively lower the anchor22 within the well, and it is a feature of the anchor that itaccommodates itself to such movement by progressive movement of the slip32 downwardly relative to the bore 31 with which the slip is inengagement. This occurs even though the slip is urged outwardly withgreat force due to the angularity of the Slip wickers 50 as related tothe angularity of the inner engaged surfaces of the slip and the wedgingmember at 36, the wedging member blocking inward displacement of theslip. On the other hand, it sometimes happens that the fluid pressurewithin the string 11a drops off, as for example during removal of therod string and the pump part attached thereto including the upper ball19, from the tubing, for repair or replacement of pump structure. Suchremoval of course displaces liquid from within the tubing, therebyrelieving the downward pressure on the actuator which urges the slipinto forceable gripping engagement with the bore wall 31.

In this regard, it is a further and important feature of the inventionthat the wedging member not only performs the functions described above,but it also performs the additional function of transmitting stringtension acting in a longitudinally upward direction to maintain the slipmeans wedged into gripping engagement with the bore wall during drop-offof fluid pressure application to the actuator. Note in this regard thesteep angularity at the interengagement locus 36 between the wedgingmember 34 and the slip 32. Upward tension exerted by the stretchedtubing from which production fluid has been displaced is exerted via thewedging member to the slip 32 for transfer to the casing 10, whereby theanchor connects the stretched tubing to the casing even thoughproduction fluid is removed from the tubing. In this regard, the anchorhas the characteristics of being fluid pressure settable, as well astubing tension lockable to the casing, thereby partaking of the mostadvantageous features of fluid pressure and mechanically responsiveconnection to the casing while eliminating otherwise undesirablefeatures of fluid responsive and mechanically responsive anchorconnections. To relieve the connection, with the tubing under tension asdescribed, it is only necessary to lower the tubing in the Wellsufficiently to induce disconnection of the anchor from the Well bore.Such lowering may be effected by dropping the tubing at the well head,as for example, by removing the slips 53 to allow lowering of the tubinguppermost section sufliciently, and then reinserting the slips 53 toagain support the tubing in the structure 54. This action serves to backthe wedging member 34 away from the slip 32, allowing the slip to beraised by the actuator spring 43 to the position seen in FIG. 2.

A further feature of the invention permits emergency withdrawal of theanchor from the well despite the fact that the anchor is connected tothe well bore as described above. This feature makes use of a particulartype of connection between the wedging member 34 and the body 23, theconnection being characterized and shearable in response topredetermined longitudinal force transmission by the connection imposedas a result of forceable elevation of the body 23 in the well. In otherwords, a wildciently sharp upward pull on the tubing string will serveto shear the connection referred to, allowing backing away of thewedging member 34 relative to the slip 32 to release the connection ofthe slip to the Well bore.

In this regard, a particularly advantageous shear connection isillustrated as including a rod 60 connected to and extending downwardlyfrom the wedging member 34, the rod passing through a bore 61 in a lowerportion 23a of the body 23. The rod 60 is normally suspended in positionto hold the wedging member fixed in the position seen in FIG. 2 by meansof a shear ring 63 supported at 64 by the body lower section 23a. Theshear ring is received within an annular groove 65 formed in the rod asillustrated, whereby the shear ring shoulder supports the rod at thelocation 66. Under these conditions, the wedging member 34 functions inthe manner described above. When the tubing and the body 23 are pulledsharply upwardly in an emergency, the ring 63 is sheared by the rodshoulder 67, and the wedging member drops relative to the body as seenin FIG. 4, thereby allowing disconnection of the anchor from the casing.

Finally, an abutment 70 suitably attached to the tubing 11a as seen inFIG. 4 projects beneath the rod cap 71 to capture the anchor and preventits dropping in the hole should the body 23 loosen from the tubing.

I claim:

1. In a tubing anchor adapted to be installed in a well casing, thecombination of:

a tubular member adapted for connection at its ends to a string of welltubing,

a body fixed to and encircling a portion of said tubular member, thebody having a pair of circularly spaced casing-engaging arms at one sideand a single slipreceiving recess at the other side,

a hydraulic actuator at one side of said tubular member in axialalignment with said recess, and having a part movable in said recess,

a wedge member mounted on one side of the body member in axial alignmentwith said recess,

a movable slip in said recess interposed between said actuator and saidwedge member and slidably connected to both, said slip having acasing-engaging face provided with wickers permitting downward movementof the slip relative to the casing,

and passage means for transmitting fluid under pressure from theinterior of said tubular member to said hydraulic actuator whereby theslip may be moved radially outward with respect to said body to bringsaid slip face and said arms into casing-engaging position.

2. The tubing anchor of claim 1 in which the hydraulic actuatorcomprises a piston and cylinder assembly and a coil spring, all mountedoutside the tubular member and parallel thereto.

3. The tubing anchor of claim 1 in which the wedge member is fixed to arod axially slidable on the body and axially aligned with said recess,and means including a shear ring encircling the rod for releasablyholding the rod against movement relative to the body.

References Cited UNITED STATES PATENTS 1,619,268 3/1927 Rasmussen 1662172,332,749 10/1943 Page 166212 2,350,973 6/1944 Brumleu et a1 166\212 X2,435,899 2/1948 Page 166212 2,624,409 1/1953 ONeill 166212 X 2,765,85510/1956 Reed 166217 3,045,758 7/1962 Muse 166-Q17 X 3,136,364 6/1964Myers 1662l2 X CHARLES E. OCONNELL, Primary Examiner.

I. A. CALVERT, Assistant Examiner.

US. Cl. X.R. 1662 17

